These closures having hooks generally comprise on one side a lever-puller carrying a buckle affixed to a base through an axis, on the other side a hooking element or hook for the lever buckle, both being able to be affixed either directly on the upper or the shell, or to the end of a flange or flap. Offering great facility of manipulation to open and close as well as a powerful tightening, these hook closures have been generally used in almost all ski boots having a shell. By virtue of this use on a board scale, these hook closures have been improved and certain of them have in particular been provided, among other improvements, with fine and coarse adjustment means, means for returning into a position pressed against the shell, and control lever-puller with constant lever arm.
By way of example, hook closures thus improved have been described in Italian patent 186,291 and U.S. Pat. No. 4,051,611. These documents describe closures which comprise, on a flange of the shell, a lever stretcher, a hooking buckle, a linkage tie rod positioned between the lever-puller and the said buckle, a return spring interacting between the tie rod and the lever-puller, and a base affixed on the corresponding flange of the shell of the boot, linkage axes affixing the lever-puller of the said base, and the tie rod of the lever-puller. An analogous hooking element having a rack constitutes the closure hook and is pivotably affixed on the other flange of the shell, such that the tightening force which is applied to its by the buckle when the lever is closed causes its alignment. In these closures, the tie rod is composed of two elements assembled to one another by a nut-bolt linkage to adjust micrometrically the active length of the tie rod; in this way, the coarse tightening adjustment occurs from "notch by notch" on the hooking element and the fine adjustment occurs micrometrically by screwing the elements of the tie rod to a greater or lesser degree.
Such hook closures are satisfactory because, on the one hand, the tightening force can be adjusted with precision without causing modification of the length of the lever-puller arm, and on the other hand, the lever-puller with its tie rod and its hooking buckle always and automatically return to a protective press down position against the shell when it has been opened by virtue of the return spring with which it is provided.
However, these closures have been found to be complex and therefore costly particularly since it is necessary to utilize a plurality of them on a single boot. Thus, as explained in U.S. Pat. No. 4,051,611, the possibility of reducing the number of closures by employing larger elements has been proposed. This solution, which necessitated a greater alignment precision between the hook and the buckle of each closure of the known prior art because none of the latter had the ability to be oriented in the direction of the tightening force, is nevertheless not satisfactory; indeed, the fact of broadening the constituent elements of the closure of U.S. Pat. No. 4,051,611 and affixing the hook or hooking element to the shell in a pivotable manner resolves only the problem of alignment and not that of the distribution of the load by the closure element over a greater portion of the shell of the boot, because the pivotable affixation means of the hooking element, itself, does not have an enlarged surface; it is the same for the affixation means of the cap of the lever-puller even though it is not pivotable.
Of course, there are more simple closures such as those described in Italian patent 1,054,289 but, in this case, the majority of improvements previously described, particularly the fine adjustment and the elastic return to the position pressed down against the shell of the boot do not exist. In effect, in this type of closure the lever-puller formed out of steel wire is directly hooked and journalled on a notched base and two lateral windings constituting the linkage bearings of the hooking buckle which is engaged in one of the notches of a rack type hook.
This type of closure is thus simple and inexpensive but without certain improvements, such as the return to the position pressed against the shell, which are the success of almost all of the know buckle closures.